How long does it work for?

Official answer

by Drugs.com

Xtandi (enzalutamide) is a hormone therapy used for the treatment of advanced prostate cancer. It is used to treat prostate cancer that has not spread, but which no longer responds to therapies designed to lower testosterone. It is also used to treat metastatic prostate cancer or prostate cancer that has spread to other parts of the body.

Five-year survival rates are nearly 100% for men with prostate cancer that has not spread or has only spread locally. However, in cases where prostate cancer has spread to distant sites around the body, the five-year survival rate is 31%.

Xtandi is used to improve overall survival in men with advanced prostate cancer and delay the progression of the cancer.

Xtandi length of treatment - how long can you take it for?

Xtandi comes in the form of a capsule or a tablet, which is taken once a day alongside a gonadotropin-releasing hormone (GnRH) analog or bilateral orchiectomy.

Xtandi is typically taken until prostate cancer starts to progress or spread (metastasize), or until the patient can no longer tolerate therapy because of the side effects or adverse events it causes.

See the table below for details from various clinical trials about the length of time it took patients to show signs of disease progression when treated with Xtandi.

How long is Xtandi effective?

In clinical trials, Xtandi was effective at delaying the time to disease progression in men with advanced prostate cancer. In men who had not received prior treatment with chemotherapy, Xtandi was also effective at delaying the need for treatment with a cytotoxic chemotherapy agent.

During clinical trials radiographic imaging was performed regularly to pick up disease progression. PSA (prostate-specific antigen) levels were also measured.

Study name	Results
PROSPER trial - Xtandi vs placebo in men with non-metastatic castration-resistant prostate cancer (nmCRP)	Treatment with Xtandi resulted in a median metastasis-free survival time of 36.6 months versus 14.7 months in the placebo group (95% CI 0.24-0.35; p<0.001). Men treated with Xtandi survived for longer before treatment became ineffective and their prostate cancer started to spread. Men treated with Xtandi had a 71% lower risk of metastasis or death than placebo-treated patients. The time to first-use of subsequent chemotherapy was 39.6 months in the Xtandi group compared with 17.7 months in the placebo group (p<0.001).
AFFRIM trial - Xtandi vs placebo in men with metastatic castration resistant prostate cancer (mCRPC) after chemotherapy	Treatment with Xtandi resulted in a longer progression-free survival time than placebo (8.3 months versus 2.9 months, p<0.001).
PREVAIL trial - Xtandi vs placebo in men with mCRPC who have not have chemotherapy	A progression-free survival rate of 65% was observed at 12 months among Xtandi-treated patients compared with a 14% rate among those receiving placebo. Treatment with Xtandi also helped delay the need for cytotoxic chemotherapy. The median time until the initiation of chemotherapy was 28 months in the Xtandi group compared with 10.8 months in the placebo group (p<0.001).
TERRAIN trial - Xtandi vs Casodex (bicalutamide) in men with mCRPC	Treatment with Xtandi improved median radiographic progression-free survival compared with treatment with Casodex (15.7 months vs 5.8 months, p<0.0001).
ARCHES trial - Xtandi vs placebo in metastatic castration-sensitive prostate cancer (mCSPC)	The median radiographic progression-free survival time was not reached in men treated with Xtandi compared with men treated with placebo, in which it was 19 months. Treatment with Xtandi significantly reduced the risk of radiographic progression or death compared with placebo (hazard ratio, 0.39, CI 95% 0.30 to 0.50, p<0.001).

How long does Xtandi extend life?

In the AFFIRM trial, treatment with Xtandi extended life by almost 5 months. Treatment with Xtandi resulted in a median overall survival time of 18.4 months (95% CI 17.3 to not yet reached) compared with 13.6 months (95% CI 11.3 to 15.8) in the placebo recipients (p<0.001). The trial was conducted in men with mCRPC who had previously received chemotherapy.

In the PREVAIL trial, 72% of Xtandi recipients were alive at 12 months compared with 63% of those started on placebo (CI 95% 0.60 to 8.84; p<0.001). The trial was conducted in men with mCRPC who had not received chemotherapy and was stopped at 12 months, by which point Xtandi was shown to be better than placebo.

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